A delivery device for and method of providing for delivery of substance to the central nervous system (CNS) of a subject, the delivery device comprising: a nosepiece unit (17) for insertion into a nasal airway (1) of a subject and comprising an outlet unit (21) which includes a nozzle (25) for delivering substance into the nasal airway of the subject； and a substance supply unit which is operable to deliver a dose of substance to the nozzle: wherein the delivery device is configured such that at least 30% of the dose as initially deposited in the nasal airway is deposited in an upper posterior region of the nasal airway, thereby providing a CNS concentration of the substance, and hence CNS effect, which is significantly greater than that which would be predicted from a counterpart blood plasma concentration of the substance.
